One real strong contraction

Me

I’m 40+4 and been having Braxton Hicks for 2 weeks without pain. Occasional cramping. Today I was having a non stress test and had a real contraction. It hurt my tummy and wrapped round my back. I almost cried. I was in pain for at least 30 seconds or more.

Then nothing since. Just more Braxton Hicks. What gives??? Still 2 cm dilated- same as Wednesday.